The objectives are 1) to determine whether Sr and F alone and in combination speeds up the remineralization of enamel white spots and 2) to test the rate of demineralization and remineralization of enamel with and without Sr and F, alone and in combinations, 3) to determine the effect, distribution and rate of change of ions (Ca and P or Sr and F when involved) within a diffusion barrier and the underlying dental enamel during demineralization and remineralization and 4) to determine whether the remineralized enamel has acquired added resistance to an acid challenge. BIBLIOGRAPHIC REFERENCE: Little, M.F. and Barrett K. Strontium and Fluoride Content of Surface and Inner Enamel versus Caries Prevalence in the Atlantic Coast of the United States of America. Caries Res. 10:297-307, 1976.